In order to meet government mandated exhaust gas emission standards, the exhaust gases of an automotive internal combustion engine must be treated before emission into the atmosphere. Exhaust gases are routed through a catalytic converter device. The exhaust gases generally contain undesirable emission components including carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). As a means of simultaneously removing the objectionable CO, HC, and NOx components, various “three-way” catalysts have been developed. Such catalysts can employ one or more platinum group metals (PGM) such as platinum (Pt), palladium (Pd), and rhodium (Rh). As such, the undesirable components can then be converted to less harmful or non-harmful ones.
Direct injection gasoline (GDI) engines and diesel engines offer fuel economy and reduced carbon dioxide (CO2) emission. The exhaust from GDI and diesel engines contains excess amounts of oxygen (O2). Although the oxidation of HC and CO are highly efficient with excess O2, the removal of NOx components is of particular concern. This can be accomplished using a NOx adsorber.